Matrix keyboard with plurality of sequences of cascaded electrical elements

Abstract

An improved multikey matrix keyboard for inputting data into a computer, wherein pressing a key places in circuit the point of intersection of a plurality of row conductors and a plurality of column conductors respectively connected to portions of separate sets of row and column sequential series of measurable electrical elements whose cumulative values correspond to the specific row and column of the pressed key. By employing a plurality of row and column key output circuits, the number of keys present in the matrix keyboard is exponentially increased.

I claim: 
     
       1. In a multikey keyboard for inputting data to a computer wherein the X and Y rank of the pressed key is determined by the closing of a corresponding key switch means that brings into the X and Y keyboard output circuit selected portions of a pair of separate series of electrical elements which respective cumulative values are subsequently measured by the computer to uniquely establish the coordinates of the pressed key, the specific improvement comprising: replacing at least one of said X or Y keyboard output circuits with a plurality of keyboard output circuits wherein each of said plurality of keyboard output circuits comprise a keyboard output terminal electrically connected to separate sequences of cascaded electrical elements and associated conductors such that pressing of a key introduces into said respective plurality of keyboard output circuits a corresponding portion of each of said separate sequences of electrical elements that in combination uniquely define the rank of the key being pressed. 
     
     
       2. An improved multikey keyboard of claim 1 wherein both the X and Y keyboard ouput circuits are replaced with a plurality of said keyboard output circuits. 
     
     
       3. An improved multikey keyboard of claim 2 wherein both the X and Y keyboard output circuits are replaced by two separate sequences of cascaded electrical elements, thus increasing the number of keyboard output terminals from two to four and simultaneously quadrupling the number of keys on the keyboard. 
     
     
       4. A multikey keyboard for inputting data into a computer comprising: (a) a plurality of normally open, key activated, switch means arranged in a matrix like configuration of rows and columns with one switch means for each key of the keyboard;   (b) a plurality of n row output circuits wherein each of said row output circuits comprise an output terminal electrically connected to separate cascaded conductors and measurable electrical elements and wherein each of said n row output circuits are operatively connected to each of said plurality of switch means such that the set of cumulative measurable electrical elements between each key and respective output terminal define a unique combination of n values which serve to identify the respective row of said keys;   (c) a plurality of m column output circuits wherein each of said column output circuits comprise an output terminal electrically connected to separate cascaded conductors and measurable electrical elements and wherein each of said m column output circuits are operatively connected to each of said plurality of switch means such that the set of cumulative measurable electrical elements between each key and the respective output terminal define a unique combination of m values which serve to identify the respective column of said key; and   (d) a common source circuit operatively connected to each of said plurality of switch means such that when a key is pressed the corresponding normally open switch means closes, thus completing the circuit between said common source circuit and that portion of said n row output circuits and m column output circuits that serve to identify the row and column of the pressed key, thus allowing the computer to establish which key was pressed by measuring the n plus m cumulative electrical property values, where n and m are integers.   
     
     
       5. A multikey keyboard of claim 4 further comprising a sensor output circuit operably connected to each of said plurality of said key actuated, switch means which when a key is pressed completes the circuit between said common source circuit and said sensor output circuit, thus outputting a separate signal to the computer indicating that a key has been pressed and that said n plus m cumulative electrical property measurements should now take place. 
     
     
       6. A multikey keyboard of claim 1, 2, 3, 4 or 5 wherein said keyboard further comprises two opposed printed circuit sheets separated by an insulated sheet perforated at the positions of the keys such that said switch means is created by having at least one of said opposed printed circuit sheets being sufficiently flexible such that said flexible sheet may be pressed at the position of said key, thus completing the electrical contact between said common source circuit and said output circuits by physically contacting said printed circuit sheets to each other. 
     
     
       7. A multikey keyboard of claim 6 wherein the individual values of said measurable electrical elements within said sequential series of cascaded electrical elements are increased nonlinearly as they approach said respective output terminals such as to further enhance the computer's ability to discriminate which key was pressed.